Saphenous vein

Technique
Summary
Resources and references
Saphenous vein sampling in other animals
All blood sampling techniques in the guinea pig

Please read the general principles of blood sampling page before attempting any blood sampling procedure.

Technique

Sampling from the lateral saphenous vein is a relatively quick method of obtaining blood samples from all strains of guinea pig. It does not require the animal to be warmed.

Slides and videos of restraint, shaving and sampling for this technique with mice are available on the websites of the Norwegian Reference Centre for Laboratory Animal Science.

Blood is collected from the lateral saphenous vein, which runs dorsally and then laterally over the tarsal joint.

Conscious guinea pigs should be restrained either manually or using a restraint tube. This can cause stress and therefore the duration of restraint should be minimised. Where a restraint tube is used, it should be appropriate for the size of the guinea pig. All forms of restraining equipment should be frequently washed to prevent pheromonally-induced stress or cross-infection.

To collect blood, the hind leg should be immobilised in the extended position by applying gentle downward pressure immediately above the knee joint. This stretches the skin over the ankle, making it easier to clip and immobilise the saphenous vein. Please note that hair removal by shaving with a scalpel blade is no longer recommended as it removes the epidermal layers of the skin. An aseptic technique should be used. Anaesthesia is not necessary but may be used on welfare grounds for animals that are difficult to hold. Where sedatives contain peripheral vasodilators, doses should be low to avoid prolonged bleeding from the puncture site. The number of attempts to take a blood sample should be minimised (no more than three needle sticks in any one attempt). Blood is collected by capillary action into a haematocrit tube or passively into a tube.

Blood flow can be stopped by gentle finger pressure over the puncture site, or simple relaxation of the operator's grip on the animal's leg. Animals should not be returned to their cage before the blood flow has stopped.

No more than four blood samples should be taken within any 24-hour period. If more samples are needed, then temporary or surgical cannulation should be considered. The scab or blood clot is removed for multiple samples.

Guinea pigs may show temporary favouring of the limb following sampling from the saphenous vein.

Summary

Number of samples	No more than four blood samples should be taken within any 24-hour period, depending on sample volumes.
Sample volume	A single sample equivalent to 0.5% of the animal's bodyweight may be taken, which can usually be repeated at fortnightly intervals without disturbances to its haematological status. Alternatively, daily samples corresponding to 0.05% bodyweight may be taken.
Equipment	23G needle or lance
Staff resource	One person is required if a restraint tube is used. Where manual restraint is used two people may be required: one for handling the guinea pig and one for taking the blood sample.
Adverse effects	Bruising Haemorrhage Infection Temporary favouring of the limb